Fix a Python bindings bug created by the introduction of 'svn_fs_open()'.
Fix a Python bindings bug created by the introduction of 'svn_fs_open()'.

* subversion/bindings/swig/python/svn/fs.py
  (FileDiff._dump_contents): Use '__builtin__.open()' to avoid a
    name-clashing with the stripped-down svn_fs_open() call (which,
    having had its 'svn_fs_' removed, looks quite like 'open()'.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion